A Cholesterol - Breast Cancer Connection

Having high cholesterol raises the risk of breast cancer and appears to fuel its spread. Statins may help.

Obesity and overweight are known risk factors for just about any kind of cancer. Scientists believe the relationship occurs because fat cells produce the hormone estrogen, which fuels the growth of cancer cells.

Now a new study shows that simply having high cholesterol can raise a woman’s breast cancer risk, no extra pounds needed. A byproduct of cholesterol functions like the hormone estrogen, stimulating the growth and spread of the most common types of breast cancers.

So it's probably more important than ever to manage your cholesterol, whether you are overweight or not.

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Getting cholesterol down may be one way to increase the effectiveness of anticancer drugs.

“A lot of studies have shown a connection between obesity and breast cancer, and specifically that elevated cholesterol is associated with breast cancer risk, but no mechanism has been identified,” said study author Donald McDonnell. He and his team at the Duke Cancer Institute were able to identify the chemical culprit in cholesterol that can raise a woman’s risk.

“What we have now found is a molecule — not cholesterol itself, but an abundant metabolite of cholesterol.”

The metabolite, a natural by-product of cholesterol metabolism in the body, is called 27-hydroxycholesterol, or 27HC, and it seems to mimic the way estrogen functions and thus encourages the growth of cancer cells.

The research team exposed a group of mice to 27HC and noted that they developed breast cancer more often. Exposure also affected how likely the cancer was to spread to other organs.

When the researchers stopped administering 27HC, or when they gave an antiestrogen compound, the activity of the compound decreased, suggesting that 27HC is indeed an estrogen mimic.

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The same results were found when the team used actual human breast cancer cells. In fact, in human cells, the more aggressive the tumor, the more the cells needed higher levels of an enzyme involved in 27HC production.

This may be the reason, the team suggests, that anti-cancer drugs like Tamoxifen, an antiestrogen medication, can lose effectiveness.

What is significant about the finding, McDonnell said, is that it means that breast cancer cells are essentially using a compound besides estrogen to fuel their growth.

The results, though hardly good news, do suggest that statins and other cholesterol-lowering drugs may offer benefits beyond those to the heart.

For women who have breast cancer and high cholesterol, the authors say, getting cholesterol down may be one way to increase the effectiveness of anticancer drugs like Tamoxifen. And if you don’t, managing cholesterol is still critically important.